Which directory

I’ve been playing around with instant WP for a couple of weeks and I’m now fairly confident in how to use it. So I purchased my first domain name and some hosting at hostgator. I am looking to create a static home page with a picture header, some text and a PDF file for visitors to download.

My question is: Do I install WP in the root directory, or in the Sub directory, does it matter and will it make a difference to my website?

Thanks in advance for your help